DreamWorks' 'The Croods' all but assured top spot this weekend

A scene from the animated 3-D film "The Croods," which is set to rule the box office this weekend.

A scene from the animated 3-D film "The Croods," which is set to rule the box office this weekend. (DreamWorks Animation)

"The Croods" could club its way to box-office success this weekend, as the animated caveman movie looks certain to end up No. 1.

The 3-D DreamWorks Animation film is likely to open with a solid $40 million, according to those who have seen pre-release audience surveys. The weekend's other big debut, the special-effects-heavy White House action-thriller "Olympus Has Fallen," will trail behind with a so-so $20 million.

Meanwhile, two lower-budget pictures -- the Tina Fey comedy "Admission" and the R-rated party flick "Spring Breakers -- are set to launch with less than $10 million apiece.